ABSTRACT
Fused silica glass is a material of choice for micromechanical, microfluidic, and optical devices due to its chemical resistance, optical, electrical, and mechanical performance. Wet etching is the key method for fabricating of such microdevices. Protective mask integrity is a big challenge due extremely aggressive properties of etching solution. Here, we propose multilevel microstructures fabrication route based on fused silica deep etching through a stepped mask. First, we provide an analysis of a fused silica dissolution mechanism in buffered oxide etching (BOE) solution and calculate the main fluoride fractions like [Formula: see text], [Formula: see text], [Formula: see text] as a function of pH and NH4F:HF ratio. Then, we experimentally investigate the influence of BOE composition (1:1-14:1) on the mask resistance, etch rate and profile isotropy during deep etching through a metal/photoresist mask. Finally, we demonstrate a high-quality multilevel over-200 µm etching process with the rate up to 3 µm/min, which could be of a great interest for advanced microdevices with flexure suspensions, inertial masses, microchannels, and through-wafer holes.
ABSTRACT
Anomalous optical properties of microscopically inhomogeneous dielectric films placed on a thick metal sublayer are investigated. We study the reflection, scattering, and absorption of the coherent electromagnetic radiation as a function of the incidence angle. Computer simulations show the existence of the incidence angle of the laser beam when the scattering and absorption increase simultaneously for the s-polarization so that almost 60% of the incident light goes in the scattering channel. The critical angle corresponds to the excitation of Fabry-Perot mode. The effect makes it possible to manipulate the reflection from the metafilms.
